Introduction
Literature
Data
Methodology
Results
Hypothesis:
A biased media reporting in political news may have a profound influence on voter opinions and preferences
The concept of media bias encompasses different subtypes (D’Alessio and Allen, 2000): (1) Coverage bias, (2) Tonality bias, (3) Agenda bias
Research Question:
Is online media biased?
What is the effect on voting behavior?
Methodology:
Unbiased reporting:
Biased reporting:
To what extend does a reporting deviate from that benchmark?
What is the benchmark?
Coverage bias (Quantity: How often do political actors appear in the media?)
Tonality bias (Quality: How are parties evaluated?)
Agenda bias (Quality: Is a party able to present their own political positions in the media?)
Hypothesis:
Benchmark:
The amount of a parties campaign communication (Hopmann et al., 2012)
Standing in polls (Junqué de Fortuny et al., 2012)
Average visibility of all parties in each media outlet (Eberl et al., 2017)
Methodology:
Manually coded data
Textmining approach (e.g. count number of occurrences)
To estimate the effect of the bias on voting preferences…
Historial data (Dewenter et al., 2018)
Hypothesis:
Benchmark:
Methodology: - Manually coded data (Eberl et al., 2017)
Hypothesis:
Benchmark:
Methodology:
Results:
Online news articles
A party \(p\) is treated as visible in an article of newspaper \(s\) if the party itself is mentioned in an article (if an article contains the word “SPD”, “CDU”/“CSU/Union”,“FDP”,“Grüne”,“AfD” or “Linke”)
\[ \text{visibility}(p,s) = \frac{\text{#Articles}_{p,s}}{\text{#Articles}_s} \]
{width:80%}
There is a bias in a medium when a political party is overrepresented compared to other parties and other outlets
Benchmark: Average visibility of all parties in each media outlet during the period of analysis
Visibility bias: Deviation of each party’s specific visibility from the average visibility of all other parties in that outlet.
Dictionary-based method to measure the tone (or sentiment) of a document.
Dictionary is a list of words associated with positive and negative polarity weighted within the interval of \([-1; 1]\)
| word | value | |
|---|---|---|
| 1 | räuber | -0.3508 |
| 2 | zusammenhalt | 0.1947 |
| 3 | desaster | -0.3413 |
| 4 | vernichtung | -0.4883 |
| 5 | weglassen | -0.3362 |
| 6 | unzumutbar | -0.34 |
| 7 | erholen | 0.2357 |
| 8 | niederschlagen | -0.1871 |
| 9 | abstürzen | -0.4697 |
| 10 | heftig | -0.1819 |
Agenda bias refers to the extent to which political actors appear in the public domain in conjunction with the topics they wish to emphasize.
Benchmark: Policy issues addressed in party press releases as an approximation of the potential universe of news stories. .
Credits: Christine Doig
Credits: Blei (2012)
\(K\): choose the number of topics
\(\theta_d\): for each document \(d\), choose a distribution over topics;
\(z_{d,n}|\theta_d\): according to \(\theta_d\), assign a topic \(z_{d,n}\) for the \(n^{th}\) word;
\(w_{d,n}|z_{d,n},\beta,\theta\): choose a term from that topic according to \(\beta_k\)
\(N\): repead this process for all \(n\) word-positions in the document.
\(D\): conduct this process for all \(d\) documents in the corpus
Allows to include covariates into a topic model:
Topic Prevalence: Attributes that affect the likelihood of discussing topic \(k\)
Topic Content: Attributes that affect the likelihood of including term \(w\) overall, and of including it within topic \(k\)
| Joint label | News articles | Press releases |
|---|---|---|
| Topic 47 : staatsanwaltschaft polizei erklärt peter | staatsanwaltschaft polizei ermittlungen cdu | erklärt peter netzdg steudtner |
| Topic 44 : bundeswehr leyen bundeswehr bundesregierung | bundeswehr leyen soldaten nato | bundeswehr bundesregierung syrien nato |
| Topic 27 : spahn cdu gabriel macron | spahn cdu jen heimat | gabriel macron französischen deutsch |
| Topic 1 : europa eu eu europäischen | europa eu deutschland europäischen | eu europäischen europäisch button |
| Topic 2 : spd schulz groko traurig | spd schulz gabriel partei | groko traurig verzicht übernimmt |
| Topic 25 : stiftung deutschland deutschland forschung | stiftung deutschland menschen osten | deutschland forschung menschen wirtschaft |
| Topic 42 : abschiebungen deutschland pflege gesetz | abschiebungen deutschland abschiebung afghanistan | pflege gesetz erklärt jahr |
| Topic 4 : wahl bundestagswahl gewählt europarat | wahl bundestagswahl mitglied parteien | gewählt europarat parlamentarischen vorsitzenden |
| Topic 35 : welt sonntag bund bildung | welt sonntag menschen meinung | bund bildung länder schulen |
| Topic 30 : afd höcke meuthen bundesvorstand | afd höcke partei gauland | meuthen bundesvorstand partei verfassungsschutz |
For each document, we have a distribution over all topics, e.g.:
Agendas were measured in terms of percentage distributions across the 50 topics.